Taiwan split from the Chinese mainland in 1949. The U.S. policy acknowledges the Chinese view over sovereignty, but considers Taiwan's status as unsettled. China, meanwhile, considers Taiwan a rogue province. Any recognition of a Taiwanese head of state is unacceptable to China, so Trump's reference to the "President of Taiwan" was probably not what China wanted to hear.

But this also coincides with Trump's generally harsh view of China.

Did China ask us if it was OK to devalue their currency (making it hard for our companies to compete), heavily tax our products going into..

The New York Times reports a Trump Organization representative called in September to discuss potential investments in a pricey makeover of the city of Taoyuan, raising further questions of potential conflicts of interest.